Wireless signaling system.



No. 756,718. PATENTED APR. 5, 1904. H. SHOEMAKER.

WIRELESS SIGNALING SYSTEM.

APPLICATION FILED AUG. 9, 1902.

NO MODEL,

UNITED STATES Patented April 5, 1904.

PATENT OFFICE.

HARRY SHOEMAKER, OF PHILADELPHIA. PENNSXLVANIA, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO INTERNATIONAL WIRELESS TELEGRAPH COMPANY, A CORPORATION OF NEW JERSEY, A ND MARIE V. GEHRING, OF PHILADELPHIA, PENNSYLVANIA.

WlRELESS SlGNALlNG SYSTEM.

SPECIFICATION forming part 'of Letters Patent No. 756,718, dated April 5, 1904. Application filed August 9, 1902. Serial No. 119,031. (No modeh To all whom it may concern:

Be it known that I, HARRY SHOEMAKER, a citizen of the United States, residing at Philade1pl;ia,in the county of Philadelphia and State 5 of Pennsylvania, haveinventcd anew and useful \Vireless Signaling Systcm, of which the following is a specification. I

invention relates ,to electrical signaling,

more especially that known as wireless sig- IO naling, in which the energy representing the message or signal to be transmitted is modified by and in accordance with such message and impressed upon the natural media and received at the receiving-station from the natural media and employed to record a message,

either audible or visible,'by means of apparatus controlled by the arriving energy.

'My invention relates more particularly to the receiving apparatus of such a system and depends for its principle upon that of the Wheatstone bridge so commonly known in the electrical arts. V

My invention comprises a system whereby a conductor of electricity which has either a great. positive temperature coefficient or a.

great negative temperature coefficient is traversed by energy depending upon the received energy and'when so traversed by electrical energy increases or decreases its resistance, 3 and thereby throws out of balance a W heatstone bridge, resulting in a flow of current from a source through the galvanometer-ciring in general metals, and for such purposes iron, platinum, and the like may be used. I

vanometer or relay R.

In the drawing, A represents the usual aerial conductor of a wireless-signalmg sy'steln, which connects at its low-or cndwit one terminal of the substance having a high tem pcrature coeiiicient and which is represented by P. The other end of, this memlnn-P'is 5 connected to earth-plate E. This member P forms (as clearly shown) one arm of a W heatstone bridge, in the other arms of which are arranged resistances 1, 2, and 3, respectively.

At R is shown the galvanomctcr or relay as 7 located in the galvanom'ctcr circuit of the bridge. A-t B is shown a source of energy whose terminals connect to the bridge at the junction of resistances 1 and 2 and at the junctioii of P and 3. Normally when no message is being received the bridge is in balance and there is no current flowing through the gal- However, when any radiant energy is received the temperature of the device P is increased, with the consequentfi increase or decrease in its resistance, accord ing as its temperature coeiiicient is positive or negative. In either event the bridge is thrown out of balance and a current willfiow through the galvanometer or relay It. The galvanometer may be used directly as the indicating instrument or if R is a relay it can be used to control a local circuit, as is cus- I tomary in telegraph systems and the like.

a and b are choke-coils in the arms 1 and 3, 9 respectively, of the bridge. cis another chokecoil between the source B and the juncture of straight platinum wire. stood, however, that the conductor P niay be the arms Pand of the bridge. The purpose of thesechoke-coils is apparent, for they prereceived from going into undesired paths. The membenP, as I have used it, has been a It is to be undercoiled up to save space or for any other reason. 7 It is to beiunderstood also that a relatively long conductor-P may be used. Preferably a Very short length is to be used with a cross-section which is very small, indeed, so

small, in' fact, that therise in' temperature will be considerable, and th'erebycause a corresponding change n wire.

"Whatlclairnis i 1. In a wireless-telegraph receiver, th ecom- -bination with a receiving-circuit, of a Wheatstone bridge containing in one arm a conduc-' tor adapted to be heated by the receivedenergy, choking-coils in the armsof said bridge" adjacent to said first-mentioned armand'athe vresistance of such vent any of the high frequency oscillations 5 controlled by such conductor and a recording cordance with the energy received, chokingcoils in the arms or said bridge adjacent to said first-mentioned arm, a source of energy device responsive-to the changes in. the current from said source of energy.

In a wireless-telegraph receiver, the combinat on with a receiving-circuit, of a Wheatstone bridge containing in one arm a conductor adapted to be heated by the received energy, means for preventing the received energy frornpasslng to eartharound said conductor, and a recording instrument controlled by said conductor.

4:. In a r ceiver of awireless-telegraph system, the combination of a Wheatstone bridge containing in one arm a conductor having a large temperature coeificienhineans for ch anging the temperature of said conductor in accordance with the energy received, means for preventing the received energy from passing to earth aroundsaid conductor, a source of 

